Morphological features of established cultures of human squamous lung carcinoma cells and the cellular distribution of tumor-specific glycoproteins.

Phenotypic characteristics of a cloned cell line, RH-SLC-L11, established from a human squamous lung carcinoma, were studied. The line has maintained its morphologically characteristic growth pattern for over 3 years. Settling cells exhibited extensive surface blebbing during spreading and established small cell islands that eventually expanded by mitosis to confluent cultures. Cell islands and confluent cultures presented three cell types: (i) small, polygonal cells, (ii) polygonal cells of intermediary size and (iii) very large, extremely flattened, degenerating cells. Mitotic activity was present predominantly in type (i) and the sequence (i)--(iii) is presumed to represent the lines' cycle. Previous work has demonstrated that the SLC-L11 line releases tumor-associated glycoproteins and glycolipids. These could be identified with a murine Mab (43-9F). The specific epitope was determined by carbohydrate residues and was shown to have growth factor-like properties. Mab 43-9F bound heterogeneously to the surface of SLC-L11 cells: Most large cells were unreactive while both type (i) and (ii) cells showed conspicuous differences in immunostaining intensity. Immunocytochemical analysis also indicated redistribution, shedding and internalization of antigen-Mab complexes, which may have significant impact on the use of the epitope as tumor marker in diagnosis and therapy. No definite clue was obtained as to the release of the antigenic carbohydrate epitope itself.